Propellant powder and process of making the same



NoDrawing.

Patented June 14, 1932 UNITED STATES PATENT OFFICE E WAGNER, OF ALTON, ILLINOIS, ASSIGNOR TO WESTERN CARTRIDGE COM- I PANY, OF EAST ALTON, ILLINOIS, A. CORPORATION OF DELAWARE PROPELLANT POWDER AND PROCESS OF MAKING THE SAME This invention relates to propellant powders and process of making the same, and

' more particularly to powders composed of nitro-cellulose, and nitro-glycerin, adapted divide the nitro-cellulose, add thereto and mix therewith the desired amount of nitroglycerin and then subject the same to pressure so that the nitro-cellulose will become gelatinized by the nitro-glycerin. In accordance with one of the processes, the nitro-cellulose is pulped with water, the nitro-glycerin added in a fine stream of spray, the whole agitated 'to secure an emulsion of the nitroglycerin and i the attachment of the nitroglycerin globules to the nitro-cellulose particles; the water is then strained ofi, the mixture subjected to pressure or rolling, dried and cut into grains.- The pressing or rolling causes a low nitration nitro-cellulose to become gelatinize'd, but a high nitration nitrocellulose may be only partly gelatinized. It has, therefore, been the practice to add a nitro-cellulose solvent such as acetone, to enhance the gelatinization. These methods however contemplate the gelatinization of the nitro-cellulos with nitro-glycerin by mixing and pressing, which increases the density and reduces the burning rate and results in a powder havin a uniform density and burning rate throng out its mass; and the center of the grains will burn at the same rate as the exterior.

If, now, nitro-glycerin is added to ungelatinize'd nitro-cellulose, which has already been made up into sheets or cut up in grains, and if no pressure is used to break down the fiber structure, the surfaces only of the fibers will be gelatinized. This gelatinizing of the surface of the fibers will achieve a degree of waterproofing amount of nitro-glycerin equally distributed by pressure throughout the entire body of the nitro-cellulose. urface gelatinization only reduces the burning rate of the exterior of the fibers, leaving the interior unchanged. The nitro-glycerin as it gelatini'zes the mtro-celluwhich is superior to an equal p Application filed May 1, 1929. Serial No. 359,707.

lose will enetrate deeper and deeper, depending on t e viscosity of the solution and the time of treatment, temperature and other con ditions being the same. Furthermore, the gelatinization and the percentage of nitroglycerin will decrease gradually from the outside towards the center, resulting in a powder having a progressive burning rate of a definite relation to the degree of penetration of the nitro-glycerin.

' One of the objects of this invention, therefore, is to provide a process for producing powder, and a resultant powder grain, in which the nitro-cellulose is so surface-treated, i. -e. coatedjor impregnated with nitroglycerin as to secure a substantially waterproof grain having-the desired ballistic properties.

Another object is to provide a process obviating the initial fine division of the nitrocellulose but permitting the grain structure to be maintained throughout the process.

Another object is to provide a process obviating the preliminary stage in which the nitro-cellulose exists as discrete fibers by permitting the grain structure to be maintained throughout the process.

Further objects will appear from the detail description, in which will be described an illustrative embodiment of this invention; it will be understood, however, that this invention is susceptible of various embodiments other than those described.

Generally stated, in accordance with this invention, the nitrocellulose grains, and more particularly ungelatinized grains, are

, treated with a solution of nitroglycerin in a vnon-solvent for nitro-cellulose. The solvent this solvent can be, and is, subsequently evaporated. The resultant nitro-cellulose powder grain is, therefore, coated or imregnated with nitro-glycerin which partially fills the pores of the powder grain and is so deposited and in such a condition as to provide a tough and coherent coating substantially free from cracks, which will effectively reduce the hygroscopicity of the grain, while enhancing its ballistic properties.

"While the nitro-glycerin-nas a gelatinizing action on the nitro-cellulose, the grain fibers are rather surface-gelatinized. It will, howa non-solvent for nitro-cellulose; examples are benzol, methanol, ethylalcohol, etc.

As an example of one illustrative embodiment of this invention, 100 parts. of ungelatinized nitro-cellulose grains are treatedwith 115 parts ofa solution containing 28.75 parts of mtro-glycerin. The nitro-cellulose grains can be dipped in the solution and drainedto retain 115 percent of the solution, or the m-' gredients can be mixed directly in a recep-' tacle in these proportions. The wet grains are then allowed to dry, preferably in a vacuum with means for recovery of the volatile vehicle. The resultant powder grain will, therefore, contain 77.6 percent nitro-cell-ulose and 22.4 percent nitro-glycerin. In the same way any other predetermined percentbe incorporated with the nitro-cellulose. t J

. It will, therefore, be seen that the invention accomplishes its objects. A propellant powder grain is produced which is not only coated or impregnated and surface-gelatinized with nitroglycerin, but the ores of. the, owder grain are partially fille with nitro-g ycerin.

I The following hydroscopic tests show the advantageous features of the powder grains:

Percentage of moisture Alter in 907 relative wig? box (8:: Initial lday 2days Bdays Qdays Untreetedni ulose. .74 1.07 286 aw 8.08 Treated with 25% solution ofni gly in alcohol..--.-- 1. 08 1. 15 1. 16 1. 16 Treated with 40% solution otni gly Bl00 l10l......----.--.- .32 74 .81 .78 .81

It will be noted that on account of the employment of a solvent for nitro-glycerin,

which is a non-solvent for nitro-cellulose, without mixingand pressing, the surfaces only of the nitro-cellulose fibers are gelatinized. The coating or 'impregnation'is' such that the surfaces .of the fibers are gelatinized and form a protective coating of such a nature. over the body of the fiber that the hygro- 'scopicity is substantially reduced. The ballistics of powder made from ungelatinized nitro-cellulose by this process can be altered to suit the type of gun. and the character of the load by variation of the grain size and of any desired thickness,

be understood that thisinvention treatment of nitrocellulose before being cut up into grains, such as in the form of sheets it. is -particularly applicable to the treatment of ungelatinized mtro-cellulose grains of fibrous structure. The grain may be of any suitable nitrated cellulose, regardless of the source of cellulose;

e. g.," from'cotton, wood, straw, etc. While n'itro-glycerin is particularly applicable for water-proofing and impregnating or coating the grains, nitrates of polyglycerinor ethylene-glycol; or other suitable nitrates of erin may be employed. It will, therefore, be understood that the terms nitro-cellulose and nitro-glycerin are used descriptively and not limitatively. It will furthermore be understood that certain features and subcombinations are of utility and may be employed without reference to other-featuresand sub-combinations; that is contemplated by and is withinthe scope of the appended claims. It is furthermore to be understood that various changes may be made in details and operations within the scope of the appended claims without departm from the spirit of'this invention. It is, t erefore, to is not to be limited to the specificdetails'and operations described. D

Having thus described the invention what is claimed is: 1

'1. In the .art of making propellant powders, the process comprising, treating nitrocellulose grains with a solution of nitro-glyccellulose. and evaporating the non-solvent.

3. In the art of making propellant ,powders, the process comprising, surface treating nitro-cellulose grains with a solution of nitrofglycerine in a non-solvent for nitro-cellulose.

4:. In the art of making propellant powders, the process comprising, surface treating Ditto-cellulose grains'with a solution of ni-.

tro-glycerine in' a volatile non-solvent for nitro-cellulose and evaporatitngthe non-solvent.

' 5. In the art of making propellant powders, the process comprising, mixing nitroglycerine with a solvent therefor but which is a non-solvent for nitro-cellulose and treat ing nitro-cellulose grains with the mixture.

6. In the art of making propellant powders, the process comprising, mixing nitro-' glycerine with a volatile solvent therefor but which is a' non-solvent for nitro-cellulose,

treating nitro-cellulose ins with the mixture and evaporating the solvent.

7. A propellant powder grain of nitrocellulose having a substantially ungelatinized core and surface gelatinized with nitro-glycerin. v

8. A propellant powder grain of nitrocellulose, surface treated with nitro-glyoerin.

9. A propellant powder grain of nitrocellulose surface-treated with a solution of glycerin in a non-solvent for nitro-oellulose,

10. A propellant grain of ungelatinized nitro-cellulose, having a substantially ungelatinized core and surface-treated with nitro-glycerin.

11 A propellant powder grain of nitrocellulose the fibers of which are surface-colloided with nitro-glyoerin. y

In testimony whereof I afiix my signature this 12th day of April, 1929.

WILLIAM E. WAGNER. 

